Books focusing on SD-WAN, and possibly any emulators/simulators

I got asked all the freaking time about SD-WAN, and I don't really have any books or emulators/sims on the subject. Can anyone point me out to some good, reputable sources, and hopefully something to practice around a little with? I've got a few things from Juniper, but it seems to require multiple devices and servers my poor PC just can't run multiple VMs of, to make it worth it.